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P. Salabura Jagiellonian University Kraków/GSI hadron 2011

In-medium modification of hadrons experiment overview ( from cold matter to low energy HI collisions ). P. Salabura Jagiellonian University Kraków/GSI hadron 2011. Motivation. R. Rapp , J. Wambach, Adv. Nucl. Phys. 25 (2000 ). P. Muehlich et al . NPA 780 (2006).  meson.

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P. Salabura Jagiellonian University Kraków/GSI hadron 2011

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  1. In-medium modification of hadronsexperimentoverview(fromcoldmatter to low energy HI collisions) P. Salabura JagiellonianUniversity Kraków/GSI hadron 2011

  2. Motivation R. Rapp, J. Wambach, Adv. Nucl. Phys. 25 (2000) P. Muehlich et al. NPA 780(2006)  meson „cold matter” • meson • at rest p = 0.3 GeV/c „hot and dense matter” • Many predictions for sizable modifications of meson spectral function A(m, p) in cold and hot nuclear matter: broadening and „dropping mass” scenarios • A(m,p) QCD vacuum properties via QCD sum rules (B. Kaempfer talk) • Experiments: +A, p+A,A+A  mesons: ,, , , ’ • cold matter, Spring8, CLAS @ JLAB, CBELSA/TAPS, : KEK E325 , ANKE, HADES • HI collisions: DLS, HADES, Helios, CERES, Na60, STAR, PHENIX, LHC..

  3. Experimental methods • Measure meson line shape in p()+A and A+A or/and Yield w.r.t NN case p () + A e+ r/ TF e- FSI ! NO FSI !

  4. in-medium width Transparency ratio in „cold matter” • „disapearance of meson in nuclear matter” Glauber Picture; CabreraNPA733(2004)130 Production Absorption FSI of decay products ! • ISI (not for ), Pauli-blocking, Fermi-motion, secondary processes, shadowing …. • normalization to C to • reduce nuclear effects absent for e+e-

  5. Signal extraction :+A • // e+e- (CLAS @JLAB) E (1.1-3.8) 0 (CBELSA/TAPS) E (1.2-2.2) CLAS:PRL 99 (2007) 262302 CBELSA/TAPS PRL 100 (2008)192302 • no  contribution • 0 FSI removed by cut on T >150 MeV • strong  contribution (in +N  ~ 3  ) • Combinatorial background measured by like sign method

  6.  Transparency from +A CLAS <p > =1.7 GeV/c CBELSA/TAPS <p > =1.1 GeV/c CLAS <p  > CBELSA/TAPS CLAS: PRL 105 (2010) 0112301 upper limit p [ MeV/c] •  in-medium  210 MeV (in  rest frame) • coll = v N  N > (3-4 x) „free”N ! n>2 particle interaction - > low. density approx? • larger TA seen in e+e- channel- / interferences? P. Muehlich and U. Mosel, NPA773, 156 (2006). M. Kuskalov, E. Hernandez, and E. Oset, EPJ. A 31, 245 (2007).

  7. -line shape in analysis M. Thiel: Thursday session E : 900-1300 MeV close to threshold CB/TAPS: Preliminary calculations: J.Weil GiBUU arXiv:1106.1344 0  • CB - Collisional broadenning consistent with TA • shift : mass shift with density • m* = m0 (1.0 – 0.16* 0/ ) • Line shape not sensitive to in-medium width/ mass due to strong suppression of in-medium decays • Yield ~ BW(m) * decay /tot  1/2

  8. Role of regenerationin TA :  , ,’ CBELSA/TAPS E (1.2-2.2) 0 A M. Nanova: Tuesday session •  absorption NOT affected by secondary reactions • „Fast”  are absorb similarly to  , • slow  are enhanced by secondary production NN , NN(1535) • weaker absorption of ’ (’ –N coupling) : ’ in-medium :25-30 MeV

  9.  Transparency from p +A A. Polyanskiy : Tuesday session ANKE : p @ 2.83 GeV K+ K- Preliminary Phys. Lett. B 695, 74-77 (2011). 0 < < 8 0 0.6 <p  < 1.6 GeV/c lab • p + A : in-medium ~ 33 -50 MeV @ <p > =1.1 GeV/c and 0:+A (Spring-8, JLab) : in-medium ~ 23-100 MeV @ <p > 1.7 GeV/c •   28 MeV from predictions (Valencia/Giessen) - kaon loop modification

  10. e+e- pairs from p+A: HADES Preliminary M. Weber : Friday • Large acceptance for pe+e- < 1GeV/c : • not measured by CLAS, KEK-E325 CLAS,KEK 0  N*/  ? VM cocktail : HADES + PYTHIA

  11. Comparison to NN reaction M. Weber talk on Friday Preliminary 0  ,N*/ Apart from Glauber model VM Apart scaling : particle producton A AA/NNpart= N0AA / N0NN • increase at low pe+e- for  and N*,  / - secondary reactions: • NN NN , NN* NNe+e- • comparison with GiBUU (J.Weil) • At high momenta : •  () ~ () ~ 0 A0.69  0.2

  12. / region calculations: J. Weil GiBUU arXiv:1106.1344 HADES CLAS PRL 99 (2007) 262302 p>0.8 GeV/c p>0.8 GeV/c p  1 GeV/c  217 MeV HADES p<0.8 GeV/c • HADES: p + Nb : • for pe+e- <0.8 GeV/c excess over pp: secondary  from N(1520),  (1700),… • Not seen in +A due to momentum cut? •  absorption compatible with CBTAPS • (GiBuu) : in-medium  150 MeV p<0.8 GeV/c

  13. Radiation from A+A @ SPS CERES @ SPS s=8.8 GeV Na60 @ SPS s=17.3 GeV PRL 96, 162302 (2006) • At SPS energies: • excess due to pion annihilation +-   l+ l- • excess related to  meson in-medium spectral function • Na60: no change in line shape for  and 

  14.  -meson in hot and dense matter Data : Na60 acceptance corrected : EPJC 59 (2009) 607 calculations: Hess/Rapp: NPA806(2008)339. „Baryonic loops ” pion loop direct  - N* / Dalitz decays: em . Transition form factor? •  - /N* couplings play big role in „rho” melting at SPS • Do these effects contribute to e+e- production at low energies?

  15. Baryonic sources at SIS18 HADES @ SIS18 s=2.6 GeV arXiv:1103.0876 C+C Ca+Ca TAPS - „freez-out” meson cocktail HADES, DLS e+e- • Baryonic sources : (1232) ~10-20%, N(1535,..)- 1-2%, N–N bremsstr.. • Pair excess is NOT related to  - scales as pions !

  16. Isolating „true” excess Baryonic sources from N N-”reference” PLB690(2010)118 Apart = 38 0 e+e-  subtracted „reference” N e+e- + N-N bremsstr. • Normalization to N0 takes care about Apart scaling • excess of radiation in 0.12 < M < 0.55

  17. Resonance „clock” Na60 data: EPJC 61 (2009) 711 arXiv:1103.0876 HADES Apart = 38 SIS18:  clock ? Apart :15 41 78 130 177 SPS:„ clock „ : 6 generations in fireball

  18. Helicity distributions e+  * • 0 • B=1 • „excess” • : B= 1 • : B= 1 • VM: M>0.6 • B = 0 • (at SPS) e- 0 excess VM • excess has polarization consistent with 

  19. / from HADES SIS18 : ArKcl s=2.6 GeV arXiv:1103.0876 • SIS18 : deep sub-threshold  production • large / ratio ,  absorption and enhanced  production ?

  20. /e+e- from Na60 In+In @ SPS s=17.3 GeV Na60: EPJC 64(2009)1 Na60: Eur.Phys.J. C 61 (2009) 711 e+e- e+e- • SPS:  absoption at low pt , no effect for  • no changes in  meson line shape

  21.  meson line shape from HI In+In @ SPS s=17.3 GeV Na60: EPJC 64(2009)1 • no evidance for in-medium  modifications

  22. Summary • Meson transparency in cold nuclear matter shows increased meson (, ,, ’ ) widths in-medium >> free • Estimates of meson absorption cross sections in nucleus indicate NVin-medium > NVfree : significant role of n (>2)- particle interactions ? • determination of  -meson shape in cold nuclear matter requires better understanding of /N* -Ne+e- transitions and role of secondary processes-important for HI collisions ! •  absorption observed in HI collisions (low pt ) , no effects found for  • e+e- excess in A+A collisions is related to recreation of short lived resonances : „resonance” clock” :  at SPS and baryonic resonances, ( ) at SIS18 • melting of the  meson in hot and dense matter (SPS) is dominated by baryonic effects in agreement with „hadronic” scenario

  23. back-up

  24.  production inp+A ANKE : p @ 2.83 GeV : differential cross sections • not explained yield at low momentum : • secondary processes? • at high momentum better agreement with models • for p > 1 GeV : •  in-medium 50 MeV Preliminary

  25. Effects of meson-baryon interactinos

  26. =

  27. 2/dof =1.8 2/dof =2.3 /=0.7±0.2 /=0.9±0.2 • Backgroundsubtracted • Datadescribed(both nuclei) assumming/mass modificationm*=m0(1-.092/0) • fit supports  * consistent with the vacuum for / • CB shape from mixed event but w.o absolute normalization (fit parameter)! • Fit, excluding excess region, gives / <0.15 (Cu) and <0.32(C) with CL of 95% ! In contrast to other pp data /~1 p+A @ 12 GeV KEK-PS E325 M. Naruki Phys.Rev.Lett 96 (2006) 092301

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